A weather balloon is a large, inflatable balloon made of latex or synthetic materials that carries instruments to measure atmospheric conditions. These balloons are typically filled with helium or hydrogen and can rise to altitudes of 100,000 feet or more. They collect data on temperature, humidity, pressure, and wind speed, which is essential for weather forecasting. Once the balloon reaches a certain altitude, it expands and eventually bursts, allowing the instruments to fall back to Earth with the help of a parachute. The data gathered by weather balloons is crucial for meteorologists and contributes to the accuracy of weather predictions and models.